News
Engineers use ordinary glass to exploit sun’s rays

July 23, 2008 – Revisiting a once-abandoned technique, engineers at the Massachusetts
Institute of Technology (MIT) have successfully created a
sophisticated, yet affordable, method to turn ordinary glass into a
high-tech solar concentrator.

Revisiting a once-abandoned technique, engineers at the Massachusetts
Institute of Technology (MIT) have successfully created a
sophisticated, yet affordable, method to turn ordinary glass into a
high-tech solar concentrator.

The technology, which uses dye-coated glass to collect and channel
photons otherwise lost from a solar panel's surface, could eventually
enable an office building to draw energy from its tinted windows as
well as its roof.

Electrical engineer Marc Baldo, his graduate students Michael
Currie, Jon Mapel, and Timothy Heidel, and postdoctoral associate
Shalom Goffri, announced their findings in the July 11 issue of
Science.

"We think this is a practical technology for reducing the cost of solar power," Baldo said.

The researchers coated glass panels with layers of two or more
light-capturing dyes. The dyes absorbed incoming light and then
re-emitted the energy into the glass, which served as a conduit to
channel the light to solar cells along the panels' edges. The dyes can
vary from bright colors to chemicals that are mostly transparent to
visible light.

Because the edges of the glass panels are so thin, far less
semiconductor material is needed to collect the light energy and
convert that energy into electricity.

"Solar cells generate at least 10 times more power when attached to the concentrator," Baldo added.

Because the starting materials are affordable, relatively easy to
scale up beyond a laboratory setting, and easy to retrofit to existing
solar panels, the researchers believe the technology could find its way
to the marketplace within three years.

The new technology emerged in part from an NSF Nanoscale
Interdisciplinary Research Team effort to transfer the capabilities of
photosynthesis to solar technology.

The researchers' approach succeeded where efforts from the 1970s
failed because the thin, concentrated layer of dyes on glass is more
effective than the alternative — a low concentration of dyes in
plastic — at channeling most of the light all the way to the panel
edges. However, the current technology still needs further development
to create a system that will last the 20- to 30-year lifetime necessary
for a commercial product.